1. Field of the Invention
The invention relates to grounding structure for use with I/O cards, particularly to a clip type grounding means which can be attached to the frame of the I/O card before an inner PC board is assembled within such I/O card.
2. The Prior Art
IC cards, memory cards or I/O cards were popularly used in the recent years. The basic structure of such card includes generally a rectangular frame enclosing therein a PC board having electronic components mounted thereon for signal processing, and a pair of top and bottom covers attached to such frame for shielding such internal PC board therein not to expose to the outside. For circuit design consideration, the surfaces of the inner PC board, including the top and the bottom ones, generally have grounding paths thereof, so that some grounding tangs or clips, which are connected to the metal top or bottom covers, are designedly engaged thereto for electricity transmission through such metal covers of the card. A basic structure of an I/O card can be referred to U.S. Pat. Nos. 5,038,250, 5,061,845, 5,207,856 and 5,242,310.
As a matter of fact, most I/O or IC card manufacturers are PC board manufacturers who are familiar at and fabricate the inner PC board , and generally tend to buy the other parts of the card from outside part vendors in an OEM process. In other words, the outside vendor tries to make and assemble the most parts of the I/O card beforehand, and then the card manufacturer attaches the PC board to such semi-finished pre-assembly, and successively assembles the rest parts, such as the top cover, onto such I/O card to obtain a complete and final product. It can be understood that from a viewpoint of the I/O card manufacturer, it is desired to have most portions of such semi-finished I/O card pre-assembly done by the outside vendor before he can assemble his own PC board thereto for consideration of time and labor saving. In contrast, the outside vendor who makes the most parts of such I/O card, intends to save the scraps of the raw material and lower the cost when he produces and assembles the basic structure of such I/O card Under the situation that he is asked to make such semi-finished I/O card pre-assembly.
One thing which may disturbs the aforementioned part vendor, is that the means for grounding the circuit traces on the top surface of the inner PC board is required by some I/O card manufacturers. If such grounding means is in a form of tang which directly integrally extends from the top cover, as shown in some existing products, to contact the top surface of the PC board, it will not have any inconveniences to the I/O card manufacturer for assembling the PC board onto such pre-assembly and put the top cover thereon, but such grounding tang, which integrally extends from the top cover, will complicate the fabrication procedure of such top metal cover of the I/O card wherein such top cover is made from a metal plate by stamping and forming and/or bending. Additionally, such tang integrally extending from the top cover will increase scraps in raw material. In contrast, if such grounding means is in a form of a separate clip which is independently fastened to the frame of the I/O card, it will be easier to make such top cover and prevent excess scraps during stamping and forming process in manufacturing such top cover, while it is generally inevitably required for such independent grounding clip for grounding the circuit traces on the top surface of the PC board that only after the PC board has been installed into such I/O card, such separate grounding clip can be secured to the frame of the I/O card and electrically and mechanically press against the top surface of such PC board. Otherwise, an pre-assembled existing grounding clip for circuit traces on the top surface of the PC board will hinder the top-loading installation of such PC board into the frame of the I/O card. Some manufacturers dislike such separate grounding clip in their I/O card because it will take their labor and time, and may preclude their whole assembling procedure from automation only for the step of installation of such grounding clip to the I/O card, but as mentioned before, from a viewpoint of the part vendor, such separate grounding clip can save their cost and is a preferred choice. The present invention is to provide a solution of this contradiction.
An object of the invention is to provide a separate grounding clip for circuit traces on the top surface of the inner PC board in an I/O card, which can be pre-assembled to the frame of the I/O card in the part vendor's place as one part of the semi-finished pre-assembled I/O card, and then the I/O manufacturer can assemble the internal PC board to such semi-finished pre-assembly without any obstruction resulting from such grounding clip while such ground clip can press tightly against the top surface of the corresponding PC board for grounding in the final completed I/O card after the top cover is assembled thereto.